(?s)applies the following effective flags to the remainder of the pattern: gms s modifier: single line. Allows a dot to match line terminators
-+the literal - (4510 / 558 / 2D16) , repeated at least once
BEGIN PRIVATE KEYthe literal text BEGIN PRIVATE KEY (case sensitive) -+the literal - (4510 / 558 / 2D16) , repeated at least once
.*?any Unicode character, repeated any number of times
-+the literal - (4510 / 558 / 2D16) , repeated at least once
END PRIVATE KEYthe literal text END PRIVATE KEY (case sensitive) -+the literal - (4510 / 558 / 2D16) , repeated at least once
g modifier: global. Finds all matches instead of stopping after the first
m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string